I just started the DHG blocks. I am using one layer cake and cutting the contrast blocks.
My blocks (before cutting the 9 pieces) are approximately 12.5".
Someone earlier indicated they measured 2 1/16" from center for the cuts. This is key - measuring from the center is vital to getting the blocks to 'square up'.
I love the MSQC tutorials, they put quilting within reach for those of us who have not been quilting since birth. I do find I must watch them over and over again to 'get it' right. Fortunately I have a tablet I can carry into the sewing room.